I've ran Vessery and Rexler with Expertise, /D title w/ Ion Cannon, plus an Academy to block. They put up quite a fight against a Warden+Fat Han list, but Han came out on top in the end. I only had the one game, so would love to keep at it and see if I can make it work better.
Would also consider trying out x7, and maybe upgrading the Academy to a Striker.
My problems with Expertise are the 4pt cost (very steep), and the fact that stress shuts it off. There's a fair bit of stress control out there at the moment, so I think the investment of points is too high a risk for most of the pilots I'd consider giving it to.
It needed the stress kicker to make it useless to the likes of Dengaroo. Imagine that build with expertise....
I think it has its place, it's not an auto include in every list though.
My problems with Expertise are the 4pt cost (very steep), and the fact that stress shuts it off. There's a fair bit of stress control out there at the moment, so I think the investment of points is too high a risk for most of the pilots I'd consider giving it to.
It needed the stress kicker to make it useless to the likes of Dengaroo. Imagine that build with expertise....
I think it has its place, it's not an auto include in every list though.
dengaroo already has expertise
that's the "roo" part 
except it's also used on defense
Zuckuss, the one no one plays with, with expertise and Dengar, again, the one no one plays with has been putting out 3-5 hits a turn pretty reliably depending on range. Good way to push damage through, although the dial does leave a bit to be desired. Hotshot blaster helps with that a bit.
Your mention of Hotshot Blaster completely invalidates the rest of this post. I was debating Expertise on Zuckuss until I got to that gem 
Would Advanced Proton Torps work with Expertise?
Scum Kath likes Expertise + Dengar + Engine. She can finally re-position each turn and fire with full modifiers (The Firespray's greens don't really allow for PTL) or take an evade and trade with just about anything. I imagine that it has a home on Boba as well.
I am really eager to try Rey with Expertise, Kanan Jarrus, Finn, Millennium Falcon (SLoop) along with 42pts of Miranda Doni awesomeness...
It's good, though I paired with Norra (39pts) and put Countermeasures on Rey.
Expertise is > Predator for raw # of hits rolled, particularly if your ship is likely to get bumped (focusing all dice >>> rerolling one dice). Many ships & builds that currently use Predator will find the 1pt to upgrade to Expertise (not all - people who already auto-focus like Chiraneau, or can't use their target lock like Vader, will stick on Predator).
Stress is a marginal issue at present - most commonly it will be Asajj who frustrates Expertise. I can see stress pushing it back out of the meta at times, though.
On scum builds it competes with Attani Mindlink, I think. Expertise probably better in 2 ship lists, Mindlink probably better in 3 ship lists.
Would Advanced Proton Torps work with Expertise?
Yes. Expensive combo though.
I would think that if you are Scum and can have Dengar crew, then Expertise with Dengar Crew would be fantastic. It's the best of both worlds.
Thus far it's the Tie/D Defenders that have impressed me most with expertise. In addition to the EPT allowing them mods on both attacks, it makes their focus action a dedicated defensive action without compromising what becomes an even more effective double hit. And since their most useful moves (namely the white k) are all white, the worry about stressing from maneuvering isn't nearly as big an issue as on other ships who are not so lucky. But honestly it just feels a lot like a defender talent in general, X-7's who'll never be tempted to spend their focus token on or save it for an attack are that much worse to hit.
Yes, I was thinking the same thing before I got to your post. /D Defenders would love this. Col. Vessery would love this. Even /X7's would love it as they can save their Focus for defense....or Barrel Roll. Or bump.
What actually has me really excited about the new stuff is Swarm Leader. I got to fly a Vader w/ 5 Tie Fighters last night and it was a blast to play the old style way that I loved in Waves 1-2. It was brutally effective, as well.
Hobbie would also like to have Expertise. Onde he spends his TL, he can remove any stress and then use both benefits of the focus and the rerolls.